The gameconfig mod by AbdelrahmanMahmoud, along with scripthook v2, and lowering my lodscale to default genuinely brought back everything for me. Even with streamed mods still installed. 4-6 peds on trams consistently. If I spend too much time in St. Denis though, they start disappearing again. Stood in the same spot for over an hour real time, and after 10 or so trams, they became empty again.
it only breaks again if I increase the geometry lodscale (haven't tried the mod for that yet), or wear any modded player clothing. literally just these two break it for me.